"We make very little per litre. In Britain we aim for a penny but sometimes we don't even make that," said Robert Wine, a spokesman for BP . (Some analysts believe oil could reach the $135 level. See the accompanying video for more...)

Petrol prices in Britain rose to as high as $237.3 a litre in mid-July, of which 57 percent was tax. They have since come down as crude has fallen by around $20 a barrel from its $147.27 peak and as cut-throat competition between supermarkets selling gasoline has further eroded potential profits.